1. Field of the Invention
The present invention relates to a semiconductor light emitting device, and in particular to a light emitting diode (LED) formed by removing the growth substrate after sticking a semiconductor light emitting layer grown on a growth substrate to a support substrate.
2. Description of the Related Art
Conventionally, there have been LEDs (of a metal bonding or MB structure) formed by removing the growth substrate after a semiconductor light emitting laminated body grown on a growth substrate (or temporary substrate) by a vapor deposition method such as a MOCVD (Metal-Organic Chemical Vapor Deposition) method is stuck to a conductive support substrate (or permanent substrate) via a reflective mirror (for example, disclosed in Japanese Patent Application Laid-Open No. 2009-10359). The reflective mirror is provided on the opposite side from the light extraction surface, thereby improving light output extracted to the outside.
As compared with an LED made on a conductive growth substrate, an LED of the above MB structure is thin in the thickness of the semiconductor layer compared with the chip size, and hence current spread in horizontal directions (in-plane directions) is dominant, so that current is less likely to diffuse. The luminous efficiency of LEDs depends on the density of current injected into the active layer. There is the problem that because carriers injected into the active layer overflows when the current density is high, carriers contributing to light emission decrease in number, resulting in a reduction in the luminous efficiency, thus spoiling the linearity of light emission output against current. In addition, local current constriction causes a problem in reliability because it causes the proliferation of crystal defects by electric field concentration, heat generation, and the like.
Further, there disclosed is a configuration wherein a so-called counter electrode configuration where a light extraction surface side electrode and a reflective surface side electrode are arranged so as not to overlap in top plan view is taken on, thereby promoting current spread in horizontal directions (for example, in Japanese Patent Application Laid-Open No. 2008-282851 or Japanese Patent Application Laid-Open No. 2011-165853).
Yet further, for example, Japanese Patent Publication No. 4230219 discloses a semiconductor light emitting element wherein a mesa is formed in a semiconductor layer and wherein light extraction efficiency is improved using reflection by side surfaces of the mesa. An electrode configuration of an element having an insulating substrate is described in Japanese Patent Application Laid-Open No. 2004-297095.